Electrically conductive compositions and method of manufacture thereof



Oct 29) 1957 R. w. FRn-Ts ETAL 2,811,721

ELECTRICALLY VCOIDUCTIIVE COMPOSITIONS AND METHOD OF MANUFACTURE THEREOF Filed Dec. .15, 1954 4 Sheets-Sheet 1 United States Patent ELECTRICALLY CONDUCTIVE COB/[POSITIONS .ND METHOD OF MANUFACTURE THEREOF iRobert 1W. Fritts, `Elm Grove, Wis., and-Sebastian ,Karren :PortRepubliq .Md., assignors` to Basolnc., a corporationV of Wisconsin Application December 15,1954, Serial No. 475,543

-21 Claims. .(Cl.. 75.-166) This invention relates `to .semi-metallic. alloys or compositions,composed in the main of. lead and sulphur, and

alloys orcompositions of the character indicated, in which Jthemagnitudes of certain of the electrical characteristics thereof are reproducible within desired ranges therefor.

A-.furtherobject is to provide electrically conductive alloys or compositions of `the character indicated, the electrical conductivity of which maybe eitherpositive or negative, as desired.V f

--Another object yis to provide electrically conductive alloys or` compositions ofv `-the characterindicated,V Lthe resistivity lof which may Albe controlled iin-magnitude as desired.` i

-A further object iis Ato provide electrically conductive `alloys or compositions Yas aforementioned, ithe electrical characteristics, particularly with respect to polarity, of which are controllable and reproducible. o

A lfurther-objectofthe invention is Ito providefelectricallycondnctive alloys orvcompositionsas aforementioned, inwhich` desired resistivities Vthereforyarereproducible.

Another object is to :provide i electrically-conductive alloys lor compositions `of `the'` character indicated,v the thermo-electric Ipowernfof which may I be controlled in magnitudeas desired.

LA further object is -to provide electrically conductive alloys A'or compositions ias aforementioned/in which-the polarity of thermoelectric power may Vlpe either positive orv negative as desired. Y

A -further object is to-provide electrically conductive alloys or compositions vas aforementioned, having Ynew `relationships of thermoelectr'ic power: and resistivity, and whichV are `-readilyreproducible -within desired 1 ranges of such relationships.

A further object is Ato provide electrically conductive alloys or compositions, the electrical characteristics. of which A. are substantially .i independent jofA fpriorjheatf treatment. A

A Afurther object of ltheiinvention 1 concernsja rmethod of fabrication of Ithe aforementioned alloys for :compositions to provide -for the Lreproducible production :thereof Within desired -ranges Vof "thermoelectric power :and =re sistivity. i Y- j l Y A Ifurther object f is l to provide a methodv as f last amentioned lfor arbitrarily 1 rendering isuchralloys or compositions Veitherofpositive or negativefpolarity. Y

VA 'further object is to provide yalloys Yorcorripositions as aforementioned havingadequa'te mechanical-'strength forspract-ical 'applications over aiwidetemperaturelrange, A further object is to provide electrically conductive 2,811,721 Patented Oct-.29, .1957

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alloys Vor compositions of the character.abovefmentioned which are chemically'stahle over afwidetemperature .range whenshielded from oxidizing atmospheres.

A further object is fto provide electrical conductors composed of the alloys .for compositions Yof thepresent invention. l

Now, in order to acquaint those skilled in-,the art `.with lthevmanner of practicing;and;uti1izingrthe presentimention, 'thereis hereinafter disclosed ,certain preferred @me bodiments of thesinvention.

In `the drawings:

Figure 1 is a graphicsillustration generally .indicating the effect of various concentrations of1ncgative Aand;posi tive promoters with respect'to the resistivity characteristics 4of the electrically Vconductive semifmetallic alloys ors-compositions of the invention;

Figure 2 is :a graphic illustration .generally rindicating the effect of various concentrations of `negative andspositive promoters with. respect` to V.the `thermoelectric power characteristics of the electrically conductive semi-metallic alloys or compositions ofthe iinvention;

Figures 3 .and v3A are .graphic illustrations of Athe 1resistivity characteristics of .certain of fthe electrically cou,- ductive ,semi-metallic alloys or compositions of therinvvention, withincertain ranges ofadditions of negative promoters therein;

Figures 4 and 4A,ar e graphicillustrationsof: the thermoelectric ,power characteristics of :theelectrically `conclue `tiveY ,semi-metallic `alloys, `or compositions depictedf :in Figures 3 and 3A, respectively;

Figure 5 isaygraphic illustration of Vthe resistivity characteristics of certain of the electrically conductive semi-metallic alloys or compositions of the invention, within certain ranges ofadditions of positive promoters therein; and 1 Figure -6 is a Agraphic `illustration .zof thethermoelectri power characteristicsofthe electrically .conductivesemivmetallic alloysor compositions :depictedtin Figure V5.

The invention described andI claimed -herein utilizes :1a lead-sulphur ybase Vcomposition, or, alloy consisting essentially of lead in the range of 86,63% to '87.10% :by

l weight, balance fsubstantially all-y sulphur, and which base composition contains not more 'than 0.001% by AWeight of4 other matter.

Lead-sulphur base alloys within the aforementioned range and of the aforementioned purity :are negative electrical conductors and exhibit high'negative thermoelectricpower, nominally higher electrical resistivity,:,an'.d

ylow thermalconductivity with respect to .a'metaL SuchY compositions or alloys havesutility as ,electrical conductors.-

'heat treatment :aiorded lthe ralloy. during fabrication,

thereby affording control Vof such properties iby-thevheat treatment.

The aforementioned lead-sulphur alloys mayebe zest described. metallographically two-phase alloys :.It'has been Yobserved that-these alloys, .when .sectioned `and foxamined microscopically, .comprise va majornphase iconiprising crystal-grains varying-usuallysfrom `1 'to 1,0 millimeters in size andfbetween suchi-grains there1exist :thin relatively darker regionscf .-arsecondtphase.V The grains of the primary phase are :crystalsfof the rintermetallic compound lead-sulphidev .whichr.contain .approximately 86.60% 'lead vby weight. 'The darker secondfphase, clearly discernible. at fthes grain lioundarieasv is ileadncnntaininga minor Vconcentration.nf-fSulphur. f

The :function of :the .isccond'pphase z in sucht alloys is thought to be threefold. First, the thermal equilibrium between the two phases, which is established by the heat treatment aforementioned, induces negative thermoelectric power and conductivity in the primary lead-sulphide phase which, because of its high `concentration in the alloy, controls the electrical properties of the two-phase alloy. Secondly, the thin layers act as a cementing agent for the grains of the primary phase, thereby improving the mechanical strength of the alloy when compared to that of the pure intermetallic compound. This cementing action of the second phase improves the strength of an alloy in tension and compression at all temperatures up to 815 C. Thirdly, the second phase affords good electrical continuity in the polycrystalline alloy by rendering the intergranular component of electrical resistivity negligible. We have found that the actual concentration of second phase is not critical so long as the composition is maintained within the aforementioned specifed ranges.

Lead-sulphur alloys containing less than 86.63% lead by weight do not usually exhibit reproducible physical andY electrical properties when in a polycrystalline state, and in alloys containing more than 87.10% lead by weight the second phase regions are of such dimension that the electrical conductivity along the grain boundaries of the alloy connot be neglected when compared with the conductivity -through the primary phase. Moreover, unless the specified ranges of compositions and purity are adhered to, third element addition promoters hereinafter described will be rendered ineffective. Additionally, alloys having large concentrations of the aforementioned second phase are subject to plastic ow at high temperatures and for this further reason are not desirable for high temperature applications. Accordingly, the specified composition ranges and purity are to be considered critical.

It will be observed that since the electrical properties of the aforementioned alloys or -compositions are dependent upon the equilibrium temperature from which they have been quenched, use of such alloys or compositions is limited to such temperatures as will not affect the electrical characteristics established by the quenching treatment. Accordingly, for high temperature applications requiring fixed values of electrical characteristics arbitrary changes in these characteristics must be derived from the adjustment of factors other than temperature and annealing history.

We have further discovered that the electrical characteristics of lead-sulphur base alloys or compositions of the aforementioned range and purity can be markedly and advantageously altered in a reproducible manner by the addition thereto of controlled amounts of matter other than lead or sulphur. For convenience, these additions are herein designated third element additions to distinguish them from the lead and sulphur constituents of the alloys of the invention.

The third element additions which we have found effective for the purposes of the present invention when added in minor amounts to the lead-sulphur base alloy aforementioned are: Zirconium, indium, bromine, chlorine, titanium, iodine, tantalum, bismuth, antimony, gallium, columbium, uranium, sodium, potassium, rubidium and silver.

The third element additions aforementioned may be either positive promoters or negative promoters as hereinafter defined, and the resultant alloy or composition may be a positive or negative alloy or composition or conductor, as also hereinafter defined.

A negative composition or alloy and a negative conductor is to be understood through this specification and appended claims as meaning an alloy, composition or conductor which exhibits negative conductivity as evidenced by Hall effect measurements or thermoelectric effect measurements, both taken at room temperature. Similarly, a "positive composition or alloy and a positive conductor is to be understood as meaning an alloy, composition or conductor which exhibits positive conductivity as evidenced by Hall effect measurements or thermoelectric effect measurements, both taken at room temperature.

Negative promoters are those which, when added to the lead-sulphur base alloy previously defined, alter the electrical conductivity without changing the polarity of the conductivity or thermoelectric power of the base alloy (it being negative according to the preceding definition). Positive promoters are those which, when added to the lead-sulphur base alloy, cause at first, with very small additions, reduction in the conductivity of the alloy to a minimum value beyond which further increase in the concentration of the positive promoter causes an increase in the conductivity of the alloy accompanied by a reversal in the polarity of the conductivity and thermoelectric power, i. e., from negative to positive.

The functions of such negative and positive promoters should be contrasted for sake of clarity as follows:

(l) Increasing concentrations of the negative promoter elements cause increases in the conductivity and decrease of the thermoelectric power of the resulting alloy, as compared to that of the lead-sulphur base alloy, while *preserving the negative polarity of the conductivity and thermoelectric power thereof.

(2) Increasing concentrations of positive promoter elements cause initially reductions in the conductivity and increase in the thermoelectric power of the lead-sulphur base alloy, until a minimum conductivity is reached whereupon the thermoelectric power and conductivity reverse polarity to the positive sense, and further increase in the concentrations of the positive promoter causes increase in the conductivity and decrease of the thermoelectric power in the resulting alloy.

The laforeindicated effects are graphically illustrated in Figures 1 and 2, wherein the effect of varying the concentrations of the aforementioned negative and positive promoters are plotted. In both Figures l and 2, the central vertical axes give the properties of the aforedescribed base lead-sulphur alloy or composition. The left halves of each of the figures characterize the change, at room temperature, of the electrical properties of the lead-sulphur'base alloys or compositions with the addition of the aforementioned negative promoters. It will be observed that the two drawings, Figures 1 and 2, have no scales applied thereto since the concentration ranges differ for each of the third element additions to be hereinafter described due to variations in atomic weights and concentration limits. The right halves of each of Figures 1 and 2 show the changes in the electrical properties as positive promoters are added to the base alloy or composition. I-t should be noted that for a given promoter element the maximum resistivity and the polarity reversal of the thermoelectric power occur at the same concentration. This concentration is indicated by a in Figures 1 and 2.

Table I below, first column thereof, lists certain elements which we have found effective as negative promoters when added to the aforementioned lead-sulphur base alloys or compositions. Second column of Table I lists the order of the maximum concentration limits by weight percent of such promoters to the base alloy effective for achieving the objects of the invention. It is to be understood that these concentration limits are the maximum which effectively alter the electrical properties of the base alloy. Concentrations in excess of the stated amounts of such additives have no appreciable effect in beneficially altering the electrical properties with which this invention is concerned, and in this sense the limits indicated are to be considered critical. The third and fourth columns of Table I set forth the electrical properties at room temperature of lead-sulphur alloys promoted With the maximum useful concentrations of the negative promoters, after high temperature annealing as hereinafter disclosed. l

Table I Order oi Max- Thermoimum Eiecelectricv Negative Promoters tive Goncen- Power, Resistlvity,

tration Limits Micro- Ohm-Cm.

- By Weight voltsl C.

Percent zirconium 0. 40- -36 0. 00022 Indium.- 0. 50` 454 0. 00024 Bromine. Y 0. 35 -54 0. 00024 Chlorine 0. 15, -54` 0. 00025 Titanium 0. 20' 68` O. 00029 Iodine 0. 55 -99 0. 00042 Tantalum. 0. 70 -99 0. 00042 Bimuth 1 1.0-3.0 -118 0. 00061 Antimony-- 1 0. 50-3. 0 -126'k 0. 00004 Galli11m 0.30 117. 0.00058 Columbium 0. 40' l08 0. 00023 Uranium; 1. -99' 0. 00024 Figures 3,` 3A, 4 l'a.nd4A'of the drawings may be here referiredtoffor a'graphic-illustrationof the. eifect of. the additions -ofl the negative promoters lof .Table I .with respect -tothe resistivity and thermoelec-tric power characteristics (measured at room temperature) aiorded .by addition tofthe-lead-sulphurubase alloys or compositions ofjeac'h Aof thenegative promoters setforth in Table I, and with: the f variations-indicated in the. amount thereof added" in each case. As previously mentioned, certain-positive promoters may falso be alloyed with the aforementioned.lead-sulphur alloys,and such promoters are listed in'column l of .Table Il below. The secondI columnof Table II, like the. corresponding column'ofTableIjsets forth the .order of the maximum concentration limits by .weight percent.. of such promoters to the base .alloy effective for achieving theobjects-ofthefinvention. Again, it will be observed that concentrations of the positivepromoters to .the lead-sulphur-base alloy in amounts `in excess ofwthat. contained in column 2"of Table II have. no appreciable eiectin beneiicially altering. the electrical` properties With which thisinvention -isV concerned and. in .this sense the limits indicated are to be-considered critical.

Column 3 of Table Il 'sets forth the concentrationby weightfpercent ofthe positive promoters listed at which the polari-ty of conductivity andv 'thermoelectric power of the promotedialloyreverses. Theseare the concentration values forfthe promoters respectively, indicated generally lby point a in Figures. 1 and 2.

`Columns 4and 5 set-forththe thermoelectric power and resistivity characteristics at room temperature of the alloy or4 composition resulting from the addition fof the.V aforede'scribed positive promotersl in the .amount vshown in columnZI-after high temperature annealing and subsequent lslowcooling as hereinafter disclosed.

Table Il Order of Max- Concentration, vimum Eiec- Weight Per- Thermoi Positive' tive Concencent at. Which electric Resxstrvity, Promoters tration Limits Polarity Re- Power, Ohm-Cm.

` By Weight `verses (Point Micro- Pereent a Figures voltslv C. i 1 and 2) Sdiiirn- 0. 20 0. 02 +364 0. 24 Pbtassiu 0. 30 0. 04 +446 0. 32 Rubidium; 0.70 0. 20 +450 0. 20 Silver; 2. 0 0. 30 +270 0. 02

As aforementioned,'thelead-sulphur base alloy prev iouisly described is a two-phase alloy. When-the aforedeseribedthird element additions` are incorporated in the base'aalloy; `such third .element additions become distributedbetween the two.phases. We have discovered that the natureofvsuch distribution .has negligible elect uponthe:electricallproperties of the composition in all cases except` that of `bismuth and. antimony. According1y,the case-of bismuth and. antimony, the maximum effective concentration` is dependent .upon the lead. content of the---lead-sulphur base alloy-.withinuthe A`ranges stated` therefor-in TablesI andfII'. We have foundl 3'.0%11by. weight bismuth to be the maximum eiective concentration for lead-Sulphur base alloys containing 87.10%1ead; for base alloys containing less lead the maximum eiective bismuth concentrationV is somewhat less, thatis ranges down-to 1.0% by-weight` whenthe lead content-.ranges down to 86.63%. Similarly, in the case of antimony, the` maximum eiective concentration is dependent upon the lead content of the lead-sulphur base alloywithin the range stated4 therefor. We have found. 3.0%. by weight antimony to be the-maximum eiective concentrationfor lead-sulphur base alloys containing 87.10% lead; for base alloys containing. less lead the maximum effective antif mony concentration is-somewhat less,` that is rangesdown to 0.50% by weight when the lead contentranges down tov-86.63%. This behavior-of bismuth and antimony iS thought l.to be `due to the formation. of a bismuth-leadsulphur or an antimony-lead-sulphur complex withinthe. intergranular phase aforementioned whichaccounts fora portion ofthe addition. All other third element addi-1 tions `aforementioned,.both positive and negative,` formcomplexes with the second or-intergranular phase. afore-l mentioned to-a much'lesser extent thangdo bismuth;and antimony, and for purposes of this invention, inthe casesofsuch other additions theseelects areinconsequential. Accordingly, noA changes t inthe concentration limits. thereof Vare necessary as the proportions of leadand sulphurin `the base alloy vary within the range stated therefor. i

In `Tables I and Il'. above, the thermoelectric, power and resistivity datagivenis in both cases for the86.63 lead,.balance substantially all sulphur composition -containing the third element additionV in question in, the amount indicated-inthe table (in the case of bismuth and antimony, the lower maximum eective amount indicated).

Figures 5 and 6 of the drawings may be here referred to for a graphic illustration of the effect of the additions of thek positive promoters .of Table II with respect .to the resistivity .and thermoelectric power characteristics (measured atA room temperature) afforded by addition to thelead-sulphur. base alloys or compositionsv of each of the positivepromoters set forth in Table Il, and with the variations indicated in the amount thereof added. in

eachV case. Y

In connection with the a'r`orementioned` Figures 3 to A6, the logarithm of the percent by weight concentration, and the logarithm of'the resistivity have been. plotted for convenience, as will be understood by those skilled in the art, while thermoelectricpower has been plotted linearly;

It will -be observed upon examination of the datarecorded in Figures l through 6, that. a wide range of electrical properties can be induced in lead-sulphur base al.- loys bythird. element. additions, either positive or nega.- tive as desired. Indium additions, for example, can reduce theresistivity ofthe lead-sulphur base alloy by more than a factor of approximately 20 while reducing the thermoelectric power by a factor of 5.

The aforedescribed alloys or compositions and electrical conductors comprising the invention may be fabricated vby melting together the alloy constituents aforementioned, within the concentration limits aforeindicated. Itis to be understood, however, that as has beenpreviously indicated, .thelcad-sulphur alloys of the invention must be of a high order of purity, i. e., containing not in excess of the order of 0.001% by weight impurity. Such purity has been found to be necessary in practicing the present invention if the electrical properties of the alloys of this invention are .to be reproducible. It is to be understood, however, that tellurium and selenium, because of their chemical similan'ty to and natural occurrence withsulphur, are frequently contaminants in commercial sulphurandare .diicult and expensive to remove to'. theextent .of .purity` as .fspecitied abona We. have found, however, that tellurium and selenium concentrations of the order usually found in commercially pure sulphur, usually less than 1%, cause no significant changes in the electrical properties of the alloys -of this invention.

In the production of the new alloys or compositions of our invention and electrical conductors comprising the same, the constituents are melted at from l115 C. to l200 C. under a reducing atmosphere, and agitated to insure uniform distribution. The alloy may then be cast, formed or machined as desired. It is then preferably annealed to insure normalization of the alloy or composition. Such annealing may be accomplished at temperatures ranging from 540 C. to 815 C. for from 10 to 20 hours, the lesser time being required at the higher temperature. The aforementioned annealing may be con-` veniently accomplished by sealing the ingots of the alloy or composition within a quartz or Vycor envelope under an inert atmosphere.. This prevents loss of material and hence preservation of the ingots during annealing and affords a simple method of handling. The aforedescribed third element addition promoted compositions may then be slowly cooled to room temperature or quenched directly or at any intermediate temperature in cold water without substantially affecting the reproducibility of the desired electrical characteristics, especially as the concentration of the third element addition approaches its maximum effective concentration limit aforeindicated. Thus, the heat treatment history of the alloy or composition becomes of lesser importance in the third element addition promoted compositions aforedescribed as the concentration of the third element addition approaches the maximum effective limit aforeindicated.

The third element promoted alloy or composition is a two-phase alloy having improved electrical properties as compared to the corresponding properties of the leadsulphur base alloy. For example, the electrical properties of the third element addition promoted alloys or cornpositions are governed to a lesser extent by the heat treatment given the alloy, with variations in electrical properties considerably iess than the variations exhibited by the lead-sulphur base alloy to which no third element has been added. Thus, the third element additions, in effect, reduce the dependency of the electrical properties upon prior heat treatment and in this sense tend to stabilize these properties to a higher degree than that achieved in the lead-sulphur base ailoy. it may be stated as a general observation that the degree of stabilization increases with the concentration of the aforementioned third element additions up to the maximum effective amount thereof as above set forth. This lesser dependency of third element addition promoted alloys or compositions aforedescribed and of electrical conductors comprising the same, markedly increases the utility thereof for high temperature applications. In this connection, however, where alloys including positive promoters are concerned and where the application temperature approaches 570 C. concentrations of the positive promoter approaching the maximum effective limit aforementioned should be used to insure maintenance of positive polarity of the composition.

Compositions of the present invention also exhibit the desired physical properties aforementioned. More specically, they are mechanically strong and stable under operating conditions. The coeicient of thermal expansion is of the order of 20 106/ C.

We claim:

l. A composition consisting essentially of a base constituent consisting essentially of lead and sulphur, the percent by weight of lead being 86.63% to 87.10%, balance substantially all sulphur, and no more than of the order of 0.001% by weight of other matter except for a promoter selected from the group consisting of zirconium, indium, bromine, chlorine, titanium, iodine, tantalum,

bismuth, antimony, galliurn, columbium, uranium, so.-

dium, potassium, rubidium and silver in an amount effective to modify the conductivity of said base constituent not in excess by weight percent of the lead and sulphur of said promoters as follows: 0.40 zirconium; 0.50 indium; 0.35 bromine; 0.15 chlorine; 0.20 titanium; 0.55 iodine; 0.70 tantalum; 0.30 gallium; 0.40 columbium; 1.0 uranium; 0.20 sodium; 0.30 potassium; 0.70 rubidium; 2.0 silver; and bismuth and antimony not in excess of from 1.0 to 3.0 and from 0.50 to 3.0, respectively, over the aforementioned range of lead.

2. A negative electrical conductor consisting essentially of a base constituent consisting essentially of 86.63% to 87.10% lead by weight, balance substantially all sulphur, and not more than of the order of 0.001% by weight of other material except for a member selected from the group consisting of zirconium, indium, bromine, chlorine, titanium, iodine, tantalum, bismuth, antimony, gallium, columbium, uranium, sodium, potassium, rubidium and silver, with the zirconium, indium, bromine, chlorine, titanium, iodine, tantalum, bismuth, antimony, gallium, columbium, uranium, sodium, potassium, rubidium and silver, in an amount effective to modify the conductivity of said base constituent not in excess by weight percent of the lead and sulphur of said members as follows: 0.40 zirconium; 0.50 indium; 0.35 bromine; 0.15 chlorine; 0.20 titanium; 0.55 iodine; 0.70 tantalum; 0.30 gallium; 0.40 columbium; 1.0 uranium; 0.02 sodium; 0.04 potassium; 0.20 rubidium; 0.30 silver; and bismuth and antimony not in excess of from 1.0 to 3.0 and from 0.50 to 3.0, respectively, over the aforementioned range of lead.

3. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63% to 87.10% by weight lead, the balance substantially all sulphur, and a member selected from the group consisting of zirconium, indium, bromine, chlorine, titanium, iodine, tantalum, bismuth, antimony, gallium, columbium, uranium, sodium, potassium, rubidium and silver, in an amount effective to modify the conductivity of said base constituent not in excess by weight percent of the lead and sulphur of said members as follows: 0.40 zirconium; 0.50 indium; 0.35 bromine; 0.15 chlorine; 0.20 titanium; 0.55 iodine; 0.70 tantalum; 0.30 gallium; 0.40 columbium; 1.0 uranium; 0.20 sodium; 0.30 potassium; 0.70 rubidium; 2.0 silver; and bismuth and antimony not in excess of from 1.0 to 3.0 and from 0.50 to 3.0, respectively, over the aforementioned range of lead.

4. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and zirconium in an amount effective to modify the conductivity of said base constituent not in excess of 0.40% by weight of the lead and sulphur.

5. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and indium in an amount eective to modify the conductivity of said base constituent not in excess of 0.50% by weight of the lead and sulphur.

6. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and bromine in an amount effective to modify the conductivity of said base constituent not in excess of 0.35% by weight of the lead and sulphur.

7. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and chlorine in an amount effective to modify the conductivity of said base constituent not in excess of 0.15% by weight of the lead and sulphur.

8. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and titanium in an amount effective to modify 9 the conductivity of said base constituent not in excess of 0.20% by Weight of the lead and sulphur.

9. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from. 86.63% to 87.10% lead by weight, balance substantially all sulphur, and iodine in an amount eifective to modify the conductivity of said base constituent not in excess of 0.55% by Weight of the lead and sulphur.

10. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and tantalum in an amount effective to modify the conductivity of said base constituent not in excess of 0.70% by weight of the lead and sulphur.

11. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63% to 87.10% lead by Weight, balance substantially all sulphur, and bismuth in an amount effective to modify the conductivity of said base constituent not in excess of from 1.0% to 3.0% by Weight of the lead and sulphur over the aforementioned range of lead.

12. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and antimony in an amount effective to modify the conductivity of said base constituent not in excess of from 0.50% to 3.0% by weight ofthe lead and sulphur over the aforementioned range of lead.

13. A composition consisting essentially of a leadsulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially Vall sulphur, and gallium in an amount effective to modify the conductivity of said base constituent not in excess of 0.30% by weight of the lead and sulphur.

14. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63 to 87.10% lead by weight, balance substantially all sulphur, and columbium in an amount effective to modify the conductivity of said base constituent not in excess of 0.40% by Weight of the lead and sulphur.

15. A composition consisting essentially of a lead-sulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and uranium in an amount elfective to modify the conductivity of said base constituent not in excess of 1.0% by weight of the lead and sulphur.

l16. A composition consisting essentially of a leadsulphur base constituent consisting essentially of from 86.63% to 87.10% lead by Weight, balance substantially all sulphur, and sodium in an amount effective to modify the conductivity of said base constituent not in excess of 0.20% by weight of the lead and sulphur.

17. A composition consisting `essentially of a leadsulphur` base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and potassium in an amount effective to modify the conductivity of said base constituent not in excess of 0.30% by weight of the lead and sulphur.

18. A composition consisting essentially of a leadsulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and rubidium in an amount effective to modify the conductivity of said base constituent not in excess of 0.70% by weight of the lead and sulphur.

19. A composition consisting essentially of a leadsulphur base constituent consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, and silver in an amount effective to modify the conductivity of said base constituent not in excess of 2.0% by weight of the lead and sulphur.

20.7The method of controlling the electrical characteristics of a lead-sulphur composition consisting essentially of from 86.63% to 87.10% lead by weight, balance substantially all sulphur, which comprises alloying therewith at least one member from the group consisting of zirconium, indium, bromine, chlorine, titanium, iodine, tantalum, bismuth, antimony, gallium, columbium, uranium, sodium, potassium, rubidium, and silver, in an amount not in excess by weight percent of the lead and sulphur of said members as follows: 0.40 zirconium; 0.50 indium; 0.35 bromine; 0.15 chlorine; 0.20 titanium; 0.55 iodine; 0.70 tantalum, 0.30 gallium; 0.04 columbium; 1.0 uranium; 0.20 sodium; 0.30 potassium; 0.70 rubidium; 2.0 silver; and bismuth and antimony not in excess of from 1.0% to 3.0% and from 0.50% to 3.0% respectively, over the aforesaid range of lead, and then annealing the resultant composition at a temperature of from about 540 C. to 815 C.

21. A multi-phase alloy consisting essentially of a base constituent consisting essentially of lead and sulphur, the percent by weight of lead being 86.63% to 87.10%, balance substantially all sulphur, having a phase constituting primarily the intermetallic compound lead-sulphide and having another phase constituting primarily excess lead, and no more than of the order of 0.001% by weight of other matter, except for a promoter selected from the group consisting of zirconium, indium, bromine, chlorine, titanium, iodine, tantalum, bismuth, antimony, gallium, columbium, uranium, sodium, potassium, rubidium and silver in an amount elective to modify the conductivity of the base constituent not in excess by Weight percent of the lead and sulphur of said promoters as follows: 0.40 zirconium; 0.50 indium; 0.35 bromine; 0.15 chlorine; 0.20 titanium; 0.55 iodine; 0.70 tantalum; 0.30 gallium; 0.40 columbium; 1.0 uranium; 0.20 sodium; 0.30 potassium; 0.70 rubidium; 2.0 silver; and bismuth and antimony not in excess of from 1.0 to 3.0 and from 0.50 to 3.0, respectively, over the aforementioned range of lead.

References Cited in the le of this patent or the original patent Chemical Abstracts, vol. 47, pages 2591(d), 3720(c) 

1. A COMPOSITION CONSISTING ESSENTIALLY OF A BASE CONSTITUENT CONSISTING ESSENTIALLY OF LEAD AND SULPHUR, THE PERCENT BY WEIGHT OF LEAD BEING 86.63% TO 87.10%, BALANCE SUBSTANTIALLY ALL SULPHUR, AND NO MORE THAN OF THE ORDER OF 0.001% BY WEIGHT OF OTHER MATTER EXCEPT FOR A PROMOTER SELECTED FROM THE GROUP CONSISTING OF ZIRCONIUM, INDIUM, BROMINE, CHLORINE, TITANIUM, IODINE, TANTALUM, BISMUTH, ANTIMONY, GALLIUM, COLUMBIUM, URANIUM, SODIUM, POTASSIUM, RUBIDIUM AND SILVER IN AN AMOUNT EFFECTIVE TO MODIFY THE CONDUCTIVITY OF SAID BASE CONSTITUENT NOT IN EXCESS BY WEIGHT PERCENT OF THE LEAD AND SULPHUR OF SAID PROMOTERS AS FOLLOWS: 0.40 ZIRCONIUM; 0.50 INDIUM; 0.35 BROMINE; 0.15 CHLORINE; 0.20 TITANIUM; 0.55 IODINE; 0.70 TANTALUM; 0.30 GALLIUM; 0.40 COLUMBIUM; 1.0 URANIUM; 0.20 SODIUM; 0.30 POTASSIUM; 0.70 RUBIDIUM; 2.0 SILVER; AND BISMUTH AND ANTIMONY NOT IN EXCESS OF FROM 1.0 TO 3.0 AND FROM 0.50 TO 3.0, RESPECTIVELY, OVER THE AFOREMENTIONED RANGE OF LEAD. 